1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) technology, and more particularly, to a patterned vertical alignment (PVA) pixel electrode which can improve transmittance on pixel regions and enhance image display quality.
2. Description of the Prior Art
Patterned vertical alignment (PVA) is one of liquid crystal (LC) vertical alignment (VA) modes. Patterns of a thin film transistor (TFT) and a color filter (CF) form electric fields. The electric fields control an alignment of LCs. Thus, a standard polyimide rubbing technique can be omitted.
Referring to FIGS. 1A and 1B, FIGS. 1A and 1B show a conventional PVA pixel. FIG. 1A shows a schematic diagram of a structure of a first electrode 10 which is disposed on a TFT-array substrate in the conventional PVA pixel electrode. FIG. 1B shows a schematic diagram of a second electrode 20 which is reversely disposed on a color filter (CF) in the conventional PVA pixel electrode. The periphery of the conventional PVA pixel electrode is different from the inside thereof because of the structure of the conventional PVA pixel electrode. A distribution of the electric fields at the periphery of the pixel is different from that in the inside of the pixel, resulting in a fringe field effect on the LCs and disclination of LCs at the periphery of the electrodes disposed on the TFT-array substrate and the CF. Accordingly, a display quality of images is degraded and the aperture ratio of the pixel is decreased. Referring to FIG. 5A, the disclination is generated on the LCs in the highlighted areas due to the fringe field effect. So dark lines appear in the pixel, transmittance on pixel regions is lowered, and the display quality of images is degraded.
Therefore, there is a need for a PVA pixel electrode for solving problems occurring in the conventional technology.